Octane materials in Rhino. Not visible in Windows thumbnails, materials' pane previews/thumbnails or Rendered viewport

Hi RMA team,

We need a fix for a better integration of plugins, in this case in particular: seeing Octane materials in:

1. Windows explorer thumbnails
2. Rhino’s Materials tab
3. Rendered viewport

Let me please explain with examples…

We realize we need a good, fast, cheap rendering solution inside Rhino. After seeing that any of the solutions being developed by your team continue to be under our expected threshold of quality, we decided that Octane is the best alternative for us for now. (Please don’t use this topic to tell me why render engine X or Y is better than Octane, or why Rhino’s rendering solutions would work as well for us ‘if we only did X or Y’. Create your own topic for that side discussion and I’ll be happy to discuss it there)

We are happy with the rendering results in terms of what we get with ease of setup using a template scene and materials library, replicable results in various models, and clean n’ fast output with multiple render passes, even using a laptop’s GPU.

Our biggest frustration is that we are running blind when it comes to previewing materials appearance and assignment.

This is what a typical file looks like:

The render output is what we want:

Even at 32 samples (5 seconds of rendertime in this single Quadro GPU laptop) it already gives us a good sense of material, lighting and overall rendering appearance.

…however we run in to a lot of problems because we can’t see our materials in any of these places:

1. Windows explorer thumbnails
The .rmtl file type creates a silly generic orange oil paint icon (see below). This is absolutely useless for us. We need to see what the actual material looks like. Especially since Rhino uses the Windows file browser UI and appearances to interface with the libraries tab inside Rhino.

2. Rhino’s Materials tab
In this area all the thumbnails and non-existent, like here:

You can even see there in the lower part the visual garbage or repeated artifacts from trying to scroll on the options of the selected material and the pane not refreshing properly. Nothing performs adequately here.

Every once in a blue moon we see materials tarting to update, like in this case:

We have no idea what causes Rhino to update and display these thumbnails, but very very rarely happens. But even when it does happen, the thumbnails are not an accurate representation of the materials they really are.

3. Rendered viewport
Although the Octane viewport is very fast, it’s not an interactive viewport, in the sense that we cannot use it to drag-n’-drop materials, move emmisive planes (lights), or perform any edits or selection on the viewport. So we need to work with the rendered display viewport. And currently the rendered display viewport looks nothing like the rendering output, as you can see here:

I have pinpointed 3 problems. I’m not sure if these are integration problems because Octane it’s not doing their integration work completely, or because Rhino is not doing its part. This is one of the reasons I do not like using plugins, but in this case we do not see any other viable option.

Any cooperation by @andy’s team and by @paulphysicalc (developer of the Octane for Rhino plugin) would be greatly appreciated.

I can provide example files, scenes, materials, whatever assets or time you need from our part. This is a very important part of our workflow and right now is one of our biggest areas of friction. We rather see this resolved quickly so we can focus on our work.

Best Regards,


1 Like

Octane plug-in can implement preview rendering to render the thumbnails in the material editor when Octane is set to be the current renderer.

In general I agree with you that I would wish for a closer connection between octane and rhino… there are a lot of things which need improvement .

But to have an interactive viewport (in terms of updates when objects are modified) you have to change the octane settings under rhino options to

Live update: all meshes live

That should do the trick…

Edit: just realised that we’re in the Serengeti group… you are right there is a problem with the rendering not updating when the viewport is changed.

That’s good to know Nathan, we do have Octane selected as current-renderer, but this is not working now. We’ll have to ask Paul/Otoy to make this work. This would take care of the preview aspect of #2. We still need a fix for the material editor’s properties to refresh properly when scrolling, and solutions for #1 and #3.

I know not enough to say anything about #1, but a shell extension should be able to get to the embedded preview when there is one.

Item #3 can be realized building on the work done in V6 for realtime render integration. This can be done in either C++ or C#. This is something the Octane integration developer needs to do.

Hi Everyone,
I’m working with Gustavo. Here’s how Rhino v5 and v6 preview octane materials. Rhino v5 seems to be working correctly. (it wasn’t before, but I just installed the last build and it seems to be fine now)
Problem still exist in Rhino V6.


Not sure if anything major has changed for thumbnail handling. @andy, maybe you know better about that?


You have broken your file association with RMTL files. Probably by double clicking on one and associating a program other than Rhino with it at some point in the past. This destroys the thumbnail generation inside Windows Explorer windows.

Everything else is basically a bug in Octane so far as I can tell. In particular, it looks like little effort is being put into finding a display-capable representation of the Octane material. This breaks the initial preview and the rendered mode - but this is really just speculation on my part.

I’m not going to try to tell you why renderer X is better than Octane. Octane is a fabulous rendering product. We can’t, however, force 3rd party developers to support every feature of the rendering SDK properly.

Before you start blaming stuff on us, remember that all of our in-house renderers use the exact same public SDK to do the integration as 3rd party developers do. That even includes the RhinoRenderer. So if something doesn’t work as you should, you might want to check to see if it works in base Rhino first.

As I’m sure you know, I would be delighted to help resolve these problems in a calm and respectful manner. I’d love to have better integration with Octane in Rhino too.

  • Andy

Try running the command TestRestoreLibraryFileAssociations (it won’t auto-complete) in Rhino 6. That should fix the thumbnails.

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Hello Dear Andy,

I hope the evening in Europe is finding you well and that the cold winters of Finland are being handled with a good old kalsarikannit. Regarding the matters of working with computers for graphics applications, I tried the “TestRestoreLibraryFileAssociations” per your suggestion, Windows asked me to confirm if I wanted to make registry changes, I said yes. I restarted my computer and the files still have the old orange oil paint icon.

I also tried to right-click>open with on one of the .rmtl files and told it to open it with ‘Rhino BETA’. now they look like this: image

Still no thumbnails. Do you have any other ideas of what we could try?

Dear colleague @IgorK, do you happen to have the same thumbnail problem we are speaking about?

Respectfully Yours,


I did “TestRestoreLibraryFileAssociations” command too. After restart still seeing this

and here’s how rhino (not Octane) materials are showing

same here:

Standard Rhino materials are fine. Octane materials are broken

I shall test in the morning if I can reproduce with custom Raytraced materials with Cycles set as current renderer.

He, Finland isn’t a cold place anymore - even in the winter. Global warming… Very sad :no_mouth:


Are the Octane materials RMTL files?

If they are, send me one. If not - well then it’s up to Octane.


Are you living in the same Finland as me?

  • Andy

Probably, it is quite warm here.

Here’s one material



Yup - there’s no thumbnail in the file. My guess is that Octane failed to produce one.